(1) Field of the Invention
The present invention relates to a switching system which provides a call waiting service for a terminal equipment.
The call waiting service, provided by a switching system, enables a terminal equipment, which is already active in a communication, to notify its user of an incoming call from a third party. The switching system of this type acts to interrupt the existing communication and establish a connection between the terminal equipment and the third party""s terminal equipment.
(2) Description of the Related Art
As disclosed in Japanese Laid-Open Patent Application No. 9-270855, a switching system which provides a call waiting service for telephones is known. Suppose that a conventional switching system of this type interconnects a first telephone, a second telephone and a third telephone through circuit switching. When the first telephone is already active to start communication or talk with the second telephone and an incoming call from the third telephone to the first telephone occurs, the conventional switching system acts to enable the first telephone to notify its user, at a start of the communication or talk, of the incoming call from the third telephone. Further, when the first telephone is placed in an on-hook condition after the notification of the incoming call, the conventional switching system acts to establish a connection between the first telephone and the third telephone, so as to allow the user of the first telephone to communicate with a user of the third telephone.
In the above-described switching system, an incoming call from a third party is notified to the user of the first telephone at the start of the talk with the second telephone. The user of the third telephone has to wait for a reply from the first telephone until the talk with the second telephone starts and then the user takes any action. In other words, the third party will not have an answer from the first telephone so long as the communication between the first telephone and the second telephone does not start. This has been inconvenient to the user of the third telephone.
Further, in a case of an incoming call from the third telephone to the first telephone occurring in the above-described switching system when the switching system is in a state that a ringing tone is being sent to the first telephone while a ring-back tone is being sent to the second telephone after a phone number of the first telephone is dialed on the second telephone. In this case, it is impossible for the above-described switching system to provide the call waiting service for the first telephone. The user of the third telephone has to redial the number to call the first telephone again after the communication between the first telephone and the second telephone is terminated. This has been inconvenient to the user of the third telephone.
An object of the present invention is to provide an improved switching system in which the above-mentioned problems are eliminated.
Another object of the present invention is to provide a switching system which provides an improved call waiting service for a terminal equipment and is effective in speedily processing the notification of an incoming call from a third party to a user of the terminal equipment.
Still another object of the present invention is to provide a switching system which provides an improved call waiting service for a terminal equipment even when a ringing tone is being sent to the terminal equipment after the phone number of the terminal equipment is dialed on a second terminal equipment, and which is effective in speedily processing the notification of an incoming call from a third party to a user of the terminal equipment.
The above-mentioned objects of the present invention are achieved by a switching system which interconnects a first telephone, a second telephone and a third telephone through circuit switching, the switching system including: an interrupt notification unit which enables the first telephone, when a dial tone is being sent to the first telephone prior to dialing of a phone number of the second telephone, to notify its user of an incoming call from the third telephone; and an interrupt call control unit which enables a connection between the first telephone and the third telephone to be established when a predetermined number for accepting the incoming call is dialed on the first telephone after the notification of the incoming call.
The above-mentioned objects of the present invention are achieved by a switching system which interconnects a first telephone, a second telephone and a third telephone through circuit switching, the switching system including: an interrupt notification unit which enables the first telephone, when a phone number of the second telephone is being dialed on the first telephone, to notify its user, at an end of the dialing, of an incoming call from the third telephone; and an interrupt call control unit which enables a connection between the first telephone and the third telephone to be established when the first telephone is placed in an on-hook condition after the notification of the incoming call.
The above-mentioned objects of the present invention are achieved by a switching system which interconnects a first telephone, a second telephone and a third telephone through circuit switching, the switching system including: an interrupt notification unit which enables the first telephone, when a ring-back tone is being sent to the first telephone after a phone number of the second telephone is dialed on the first telephone, to notify its user of an incoming call from the third telephone; and an interrupt call control unit which enables a connection between the first telephone and the third telephone to be established when the first telephone is placed in an on-hook condition after the notification of the incoming call.
The above-mentioned objects of the present invention are achieved by a switching system which interconnects a first telephone, a second telephone and a third telephone through circuit switching, the switching system including: an interrupt detection unit which detects an incoming call from the third telephone to the first telephone when a ringing tone is being sent to the first telephone while a ring-back tone is being sent to the second telephone after a phone number of the first telephone is dialed on the second telephone; and an interrupt notification unit which enables the first telephone, which is active in a communication with the second telephone by placing the first telephone into an off-hook condition in response to the ringing tone, to notify its user, at a start of the communication, of the incoming call from the third telephone.
In a preferred embodiment of the switching system of the present invention, when a dial tone is being sent to the first telephone prior to dialing of a phone number of the second telephone and an incoming call from the third telephone occurs, the notification of the incoming call from the third telephone can be speedily made to the user of the first telephone. Further, the switching system of the present invention acts to establish a connection between the first telephone and the third telephone when a predetermined number for accepting the incoming call is dialed on the first telephone after the notification of the incoming call. Hence, the switching system of the present invention is effective in providing an increased convenience to the user of the third telephone.
In a preferred embodiment of the switching system of the present invention, when a phone number of the second telephone is being dialed on the first telephone and an incoming call from the third telephone occurs, the notification of the incoming call can be speedily made to the user of the first telephone at the end of the dialing. Further, the switching system of the present invention acts to establish a connection between the first telephone and the third telephone when the first telephone is placed in an on-hook condition after the notification of the incoming call. Hence, the switching system of the present invention is effective in providing an increased convenience to the user of the third telephone.
In a preferred embodiment of the switching system of the present invention, when a ring-back tone is being sent to the first telephone after a phone number of the second telephone is dialed on the first telephone and an incoming call from the third telephone occurs, the notification of the incoming call can be speedily made to the user of the first telephone. Further, the switching system of the present invention acts to establish a connection between the first telephone and the third telephone when the first telephone is placed in an on-hook condition after the notification of the incoming call. Hence, the switching system of the present invention is effective in providing an increased convenience to the user of the third telephone.
In a preferred embodiment of the switching system of the present invention, an incoming call from the third telephone to the first telephone is detected when a ringing tone is being sent to the first telephone while a ring-back tone is being sent to the second telephone after a phone number of the first telephone is dialed on the second telephone. Further, the switching system of the present invention enables the first telephone, which is active in a communication with the second telephone by placing the first telephone into an off-hook condition in response to the ringing tone, to notify its user, at a start of the communication, of the incoming call from the third telephone. Hence, the switching system of the present invention is effective in providing an increased convenience to the user of the third telephone.